THE WORLD; Iran the Great Unifier? The Arab World Is Wary

By MICHAEL SLACKMAN; Mona el-Naggar and Abeer Allam contributed reporting from Cairo for this article.

Published: February 5, 2006

THE streets of Tehran are decorated with black banners and black flags. Children parade through the Martyr's Cemetery with headbands that read ''Hussein'' and stores sell metal chains that some people will use to beat themselves, all part of a period of public mourning that commemorates the killing of Imam Hussein, the Prophet Muhammad's grandson, during a battle 1,300 years ago in Karbala, Iraq. That military defeat solidified a split between what became the two main branches of Islam, the Shiite and the Sunni.

Now Iran, the world's only Shiite Islamic government, is reaching across the divide, hoping to unite Arab Muslims, the vast majority of whom are Sunni, and draw them beneath an overarching banner of Islam to fight common enemies in Israel and the West.

It is a difficult sell, though, after centuries of distrust between the two sects. Moreover, a wide gap separates the Arab and Persian cultures, and a general sense of distrust lingers among Arab leaders who saw post-revolutionary Iran try to instigate unrest within their own borders.

''As a gulf area, we don't want to see Iran as the major power in the area,'' said Muhammad Abdullah al-Zulfa, a member of the Shura Council of Saudi Arabia. ''And we don't want to see Iran having this nuclear weapon where it will be a major threat to the stability of the gulf area and even to the Arab world altogether.''

As Iran's leadership pursues an aggressive, confrontational foreign policy, it is effectively trying to become a regional superpower seeking to fill the void left by the collapse of Arab nationalism and by the absence of any one dominant nation. While the United States and Europe hope that the United Nations Security Council will help tame Iran, officials here see such outside pressure as adding to their bona fides among Arab Muslims.

''The Islamic Republic of Iran is currently the axis of a tireless international identity, which relies on religious faith and challenges the global arrogances,'' said the Supreme Leader, Ayatollah Ali Khamenei, during a recent awards ceremony.

But many Arabs do not see Iran's overture that way.

While Iran has been using its drive for nuclear power to realign the balance of power in the Middle East, and trying to reinsert itself into issues of regional security that took a back seat after the Islamic revolution of 1979, Sunni Muslim leaders fear that their neighbor is trying to hem them in with a sphere of influence stretching from Iraq to Syria, Lebanon and Gaza. Their view was echoed in a comment by King Abdullah II of Jordan who said he was concerned Iran was trying to impose a ''crescent'' of influence on the region.

''If Iran developed a nuclear power, then it is a big disaster because it already supports Hezbollah in Lebanon, Hamas in Palestine, Syria and Iraq, then what is left?'' said Essam el-Erian, a spokesman for the Muslim Brotherhood of Egypt. ''We would have the Shiite crescent that the Jordanian king warned against.''

On the question of confronting the West and Israel, Iran's oratory has, in the past, resonated with many average Arabs -- and Iran has financed non-Shiite religious movements like Hamas, a Palestinian offshoot of the Muslim Brotherhood that wants to restore Jerusalem to Islamic control. Indeed, when Iran's Islamic Revolution succeeded in 1979, it lit a fire under other Muslim movements in the region, Sunni and Shiite.

Now, with President Mahmoud Ahmadinejad bashing the United States and Europe, calling for Israel to be wiped off the map and claiming that the Holocaust is a myth, many people from taxi drivers in Morocco to street sweepers in Cairo are saying that they like the man and his vision.

But once they get past that emotional response of the public, Arab leaders may well be just as disturbed by Iran's regional ambitions as any of their counterparts in the West. They also see a threat to their faith.

''If Iran acted like an Islamic power, just Islam without Shiism, then Arabs would accept it as a regional Islamic power,'' said Sheik Adel al-Mawada, a deputy speaker and member of the Sunni fundamentalist Salafi bloc in the parliament of Bahrain. ''But if it came to us with the Shia agenda as a Shiite power, then it will not succeed and it will be powerful, but despised and hated.'' Bahrain has a restive Shiite population.

The concept of a unified Arab world is often called into question when leaders gather for Arab League meetings, which seem to highlight their differences. Stepping back, the suggestion that one Islamic Middle East could unite behind a set of social, political and economic goals becomes even more far-fetched -- especially when the net includes the Iranians.

For example, Iran would like to join the Gulf Cooperation Council, a group of gulf states that try to coordinate economic policy. But the council's leadership is not eager to let Iran in, because Iran's economic clout would dwarf that of most other members.

The Arab countries know what Iran covets ''in the region in terms of oil and in terms of the sacred places,'' said Anwar Majid Eshki, head of the Middle East Center for Strategic and Legal Studies, an independent institute in Saudi Arabia.

At the moment, Iran is finding that its best chance for spreading its influence is in areas where groups actively oppose the United States. Its influence in Iraq has grown considerably with the emergence of religious Shiite movements that have done well in elections and are likely to dominate Iraq's government.

In Lebanon, Iran still has close ties to Hezbollah, the militia group turned political party that takes credit for driving Israel out of southern Lebanon.

Iran also has a strong ally in Syria. Hamas and other groups sworn to fight Israel have offices in Damascus, while Iran remains a strong supporter of Hamas, which recently won a majority of seats in the Palestinian Parliament.

The West is wrestling with whether to continue pumping millions of dollars into the Palestinian governing authority if Hamas does not renounce its commitment to destroy Israel. Some diplomats and political analysts here say the Iranians hope the West will abandon the Palestinians, because Tehran would be happy to fill the void.

In reaching for such opportunities, there also is a chance for Iran to stumble, at least in terms of its relations with its Arab neighbors. Iraq is the prime example.

While a vicious insurgency takes aim at American forces there, a battle has also begun between Iraq's Sunni minority and the Shiite majority. It has cost many Iraqi lives, and now Sunnis are watching carefully to see how Iran's influence affects their own lives.

''Iraq is the test case for Iran -- it either chooses to prove that it is an Islamic power, or a Shiite Persian power that deepens strife,'' said Sheik Mawada of Bahrain. ''Though Iran has the upper hand in Iraq, the Sunni did not just accept and keep quiet.''

Iran will have to face other challenges too, as it tries to extend its reach. If it goes too far and builds a bomb, some Iranians worry that it could set off a regional arms race and push states like Saudi Arabia to make their own bombs. Saudi Arabia has its own restive Shiite population -- living primarily in the area of its oil fields -- and does not want to see that minority empowered.

Finally, there is the matter of religion itself, and its influence on regional politics. While the initial split between Sunni and Shiite Islam occurred because of a disagreement over who would lead Muslims after the Prophet Muhammad's death, both groups have developed distinct political and social ideologies. And neither side is looking to cede any ground.

Photo: Power Play -- Ayatollah Ali Khamenei may have regional ambitions, but the Mideast's Sunni leaders are not enthusiastic. (Photo by Lynsey Addario for The New York Times)